Knife cutting mechanism for looms



Feb. 23, 1937; J. LOWRIE KNIFE CUTTING MECHANISM FOR LOOMS Filed April22, 1936 l 73 MW GN m/ m E T WM M @a Patented Feb. 23, 1937 UNITEDSTATES PATENT OFFIQE 3 Claims.

This invention relates to an improved combination of circular knives foruse in cutting the loops in the operation of weaving pile fabrics,particularly carpets. It may also be used in other machinery wheresimilar cutting work needs to be done. The particular object is to mountthe circular knives on their shaft, so that any one of them may bereplaced quickly and conveniently as compared to prior practice.

The accompanying drawing and following description will disclose thedetails of the invention.

Fig. 1 is a side elevation of a rotary cutter mounted on its shaft,showing the position of the pile wire associated therewith;

Fig. 2 is an enlarged view of one cutter mounted on the shaft with therelative position of additional cutters indicated by the dotted linesFig. 3 is a view taken substantially on line 3-3 of Fig. 2;

Fig. 4 is a view taken on line 4-4 of Fig. 3; Fig. 5 is a detail view ofone knife half; and Fig. 6 is a fragmentary view of a modified knife amounting.

Before considering the improvement, it should be understood what theprior practice is, in mechanism for cutting loops in weaving pilefabrics. It is the principal object of the present invention to improvethis particular practice. Such prior practice involves a rotatableshaft, on which a series of circular knives are keyed for rapidrotation. There is one knife for each row of pile loops. The fabric, asit is drawn over the breast beam of the loom, draws the loops formed oneach pile wire against the rotary knife for that wire. An example of theprior art mechanism is shown in the Hartley Patent 768,225, August 23,1904. It is now common practice, as indicated in that patent, to mounteach knife so as to rotate in a slot of the pile wire. The walls of thisslot spread the loop and tighten it for cutting. The tightening of theloops and their cutting by a rapidly revolving circular knife give verygood results in the character of tufts desired. While other mechanismsare in use which do not involve the rotary knives, the latter give suchgood character to the tufted fabric, that loom designers desire them inthe better type of loom constructions in spite of difficulties.

One difficulty is that if a rotary knife breaks or for any reason needsto be replaced, the repair operation not only shuts down the loom butalso uses up a lot of time. There are other difficulties that arise inrepair work when the rota y knife mechanism is used in a pile fabricloom with certain improvements in it such as shown and claimed in mycopending application Serial No. 19,967, filed May 6, 1935.

The mechanism shown in the accompanying 5 drawing is primarily designedas an improved mechanism to make the repair and. replacement of rotaryknives in the loom comparatively fast and easy, with the result that theexpensive loom can be kept in more nearly constant operation 10 withless lost time.

This is accomplished in the best manner now known to me by making acircular knife of very thin steel (like safety razor blade steel) in twoparts, 2 and 2, and removably fastening them on a holding member 3. Theadjacent parts of the knife at their ends are held against the member 3by U-shaped spring clips t, very easily put on and taken off. There is aslot 5 midway between the ends of each knife half and a correspondingnotch 5 in member 3. A spring clip has a very short flange 8, just longenough to pass through slot 5 and engage in notch 6. Otherwise, thespring clip l is like the spring clip 4, being generally U-shaped tostraddle the holding member 3 and the knife. With this arrangement itwill be seen that each knife may be mounted upon and taken off itsadjacent holding member by prying, as with a thin blade on the long legof clip l to disengage its flange 8 from holding relation to the member3. Then the knife half corresponding to that clip 1 may be lifted offthe shaft for repair or replacement. The other knife half may be treatedthe same way. The member it stays on the shaft.

It will now be clear from the unit assembly above described that theknife holding members 3 may be made to slide on the shaft, each having aflat side 9 in engagement with a corresponding fiat side of the clips 4and 1, see Fig. 4, to prevent relative rotation. Each member 3 may carrythe twohalves of one rotary knife by means of the spring clips. The baseof these spring clips may be notched into the adjacent member 3. In aloom three yards wide, by way of example, there may be nine knifeassemblies to the inch, the knife holding members may be one-sixteenthof an inch thick and each knife only a few thousandths of an inch thick.Thus, there will be about a thousand knives on the rotatable shaft. Forconvenience the drawing is on a somewhat enlarged scale for the detail.The common relation of each knife in the loom cutting operation isindicated in Fig. 1. This figure is nearly to an operating scale. Thecircular knives rotate each between the walls in the slot of each pilewire whose loops the knife serves in cutting. Thus, the pile wires spacethe knives on the operating shaft and they are not pushed together inabutting relation in their final assembly in the loom, as might appearfrom the large number on the shaft.

Now, if there is knife trouble in the loom operation, this is the way itis cured. The knife causing the trouble is readily located by the lineof the imperfect loop cutting in the product. The loom is stopped and ahand knife is used to out the loops in the rear of the knife givingtrouble. These loops are out along the top of the corresponding pilewire and also on the adjacent pile wires at each side. This hand cuttingof the loops releases the aligning tension of the loops in the producton the pile wires whose slots hold the knives spaced on the shaft. Thus,adjacent the defective knife, the knives on each side may be pried awayenough at the sides to manipulate the spring clips to remove and replacethe defective knife, or only the half injured. As already described, theknife part is taken off its corresponding holding member, and a new oneput on very easily and quickly. The member 3 stays on the shaft and isnecessarily held close to its operating position. As soon as the repairis made the loom is started up again. And the pile loops travelingforward on the pile wires with the product will realign the knifeassemblies which were only slightly disturbed from their true alignmentin making the repair. The result is that rotary knives can now be usedin this character of pile fabric looms and their use will not causedifficulties found in the prior art.

My improvement has a special advantage in combination with the loommechanism shown in my aforesaid copending application. In that mechanismthe ordinary rotary knife mechanism would have even more than the usualdifliculties in repair work. But the invention as herein disclosed isuseful for the advantages it will give in repair work of pile fabriclooms of many different specific constructions.

The principles of the invention will now be clear from the abovespecific description of how to practice it in the preferred manner. InFig.

6 I have indicated a modified form for a spring clip to hold the knifehalves on the holding memher. In this form the depressions [5, one ofwhich is shown in the fragmentary view of Fig. 6, in one leg of the clippass through holes near the ends of adjacent knife halves and pressresiliently into recesses H5 in the holding member 3. Otherwise, theconstruction is the same. The modification merely illustrates the pointthat the following claims may have a broader interpretation in somerespects than might appear from the preferred form of disclosure alone.

I claim:

1. In mechanism for the purpose described a knife holding member, a flatannular knife blade made in half portions, spring clips fashioned toremovably hold said half portions on said knife holding member, arotatable shaft on which the knife holding member is mounted, one ofsaid spring clips having such engagement with the shaft as to key theknife assembly for rotation with the shaft.

2. In mechanism for cutting loops in a pile fabric loom the combinationof a flat annular disk, a very thin annular knife blade of largerexternal diameter and substantially the same internal diameter as saiddisk, said knife blade being made in two diametrically divided halves,each half being removably held on the disk by a spring clip of U-shapedform with the base of such form engaging the internal edge of the diskand blade and with one of the legs of the clip having a short end flangesuflicient to snap into a slot in the side face of the knife blade andoverlie the edge of the disk.

8. In mechanism for cutting loops in a pile fabric loom the combinationof a flat annul r disk, 2. very thin annular knife blade of largerexternal diameter and substantially the same internal diameter as saiddisk, said knife blade being made in two diametrically divided halves,each half being removably held on the disk by a spring clip of U-shapedform with the base of such form engaging the internal edge of the diskand blade, the spring clip construction for the purpose stated havingdimples passing through holes in and aligning each knife half.

JOHN LOWRIE.

